The document discusses key concepts in data communication systems including components, data flow types, signal types, transmission media, and networking devices. It defines data communication as the exchange of data between devices via a transmission medium. The five main components are the message, sender, receiver, transmission medium, and protocols. Data flow can be simplex, half-duplex, or full-duplex. Signals can be analog or digital. Transmission media include guided media like twisted pair, coaxial, fiber optic cables and unguided media like radio waves. Common networking devices are modems, hubs, switches, and routers.

1. Topic - DATACOMMUNICATION
SYSTEMS
Subject – ADC
Code – 2161704
Branch – IC 6th
Prepared By – Gandha Dhairya (180433117005)
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2. CONTENTS
• Introduction to data communication.
• Components of data communication
• Data flow:- Simplex, Half duplex, Full deplex
• Signals:- Analog and Digital signals.
• Transmission media:- Guided and Unguided
media
• Networking devices
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3. What is Data Communications?
 Exchange of data between two devices via some forms
of transmission medium(such as wire cable) is Data
Communications.
 For data communications to occur, the communicating
devices must be part of a communication system made
of a combination of hardware and software.
 The effectiveness of a data communication system
depends on four fundamental characteristics:-
delivery, accuracy, timeliness and jitter.
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4. Components of Data
Communication:
1.Sender 2.Receiver 3.Message 4.Tramsmission Medium
5. Protocol
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5. The five components of data
communication are:
1. Message - It is the information to be communicated. Popular
forms of information include text, pictures, audio, video etc.
2. Sender - It is the device which sends the data messages. It can
be a computer, workstation, telephone handset etc.
3. Receiver - It is the device which receives the data messages. It
can be a computer, workstation, telephone handset etc.
4. Transmission Medium - It is the physical path by which a
message travels from sender to receiver. Some examples
include twisted-pair wire, coaxial cable, radio waves etc.
5. Protocol - It is a set of rules that governs the data
communications. It represents an agreement between the
communicating devices. Without a protocol, two devices may
be connected but not communicating.
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6. Data
Flow
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7. Data flow can occur in three ways:
1.Simplex:In simplex mode,the communication is
unidirectional.only one of the devices on a link can
transmit, the other can only receive. e.g.
keyboards,monitors,etc.
2.Half-duplex:In this mode,each station can both
transmit and receive,but not at the same time.When
one device is sending,the other can only receive,and
vice-versa. e.g. walkie-talkies,CB(citizens band) etc.
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8. 3.Full Duplex : In full duplex mode, both stations can
transmit and receive simultaneously. One common
example of full duplex is the Telephone network.
When two people are communicating by a telephone
line, both can talk and listen at the same time. The
full-duplex mode is used when communication in
both directions is required all the time.
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9. Signal
s
 There are two types of signals to transfer data.
Signals
Analog signal Digital signal
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10. Analog Signals
An analog signal are continuous and passes through or
includes an infinite number of continuous values
along its path. The curve representing the analog
signal passes through an infinite number of points.
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11. Digital Signals:
A digital signal can have only a limited number of
defined values. Although each value can be any
number,it is as simple as 1 and 0.

12. Transmission Media
The means through which data is transformed from one
place to another is called transmission or communication
media. There are two categories of transmission media
used in computer communications. Electromagnetic
radiation can be transmitted through an optical media,
such as optical fiber, or through twisted pair wires,
coaxial cable, or dielectric-slab waveguides. It may also
pass through any physical material that is transparent to
the specificwavelength, such as water, air, glass,
or concrete. Sound is, by definition, the vibration of
matter, so it requires a physical medium for transmission,
as does other kinds of mechanical waves
and heat energy.
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13. Types of Transmission
Media
Transmission Media
Guided Media Unguided Media
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14. Guided Media
 Guided media are the physical links through which
signals are confined to narrow path. These are also called
guide media. Bounded media are made up o a external
conductor (Usually Copper) bounded by jacket material.
Bounded media are great for LABS because they offer
high speed, good security and low cast. However, some
time they cannot be used due distance communication.
Three common types of bounded media are used of the
data transmission. These are
 Coaxial Cable
 Twisted Pairs Cable
 Fiber Optics Cable
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15. Unshielded twisted pair
(UTP)
UTP is more common. It can be
either voice grade or data
grade depending on the
condition. UTP cable
normally has an impedance of
100 ohm. UTP cost less than
STP and easily available due
to its many use. There are
five levels of data cabling
.
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16. Shielded twisted pair (STP)
 It is similar to
UTP but has a
mesh shielding
that’s protects it
from EMI which
allows for higher
transmission rate.
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17. Unguided Media
Unguided media or wireless media doesn't use
any physical connectors between the two devices
communicating. Usually the transmission is send
through the atmosphere but sometime it can be
just across the rule. Wireless media is used when
a physical obstruction or distance blocks are
used with normal cable media. The three types
of wireless media are:
 Radio waves
 Micro waves
 Infrared waves
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18. Devices used in
networking
Mainly four devices are used in networking:-
 Modem
 Hub
 Switch
 Router
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19. MODEM-(modulator-
demodulator)
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20. Modem
Amodem is a device that modulates an analog carrier
signal to encode digital information and also
demodulates such a carrier signal to decode the
transmitted information. The goal is to produce a signal
that can be transmitted easily and decoded to reproduce
the original digital data. Modems can be used over any
means of transmitting analog signals, from light
emitting diodes to radio.
There are two types of modem:-
1. internal modem
2. external modem
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21. HUB
A common connection
point for devices in
a network. Ahub
contains
multiple ports. When
a packet arrives at one
port, it is copied to the
other ports so that all
segments of the LAN
can see all packets.
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22. Switch
A network switch is a small hardware device
that joins multiple computers together within
one local area network (LAN). Network
switches appear nearly identical to network
hubs, but a switch generally contains more
intelligence than a hub. Unlike hubs,
network switches are capable of inspecting
data packets as they are received,
determining the source and destination
device of each packet, and forwarding them
appropriately. By delivering messages only
to the connected device intended, a network
switch conserves network bandwidth and
offers generally better performance than a
hub.
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23. Router
 A router is a device that forwards data
 packets between computer networks, creating an
overlay internetwork. A router is connected to
two or more data lines from different networks.
When a data packet comes in on one of the lines,
the router reads the address information in the
packet to determine its ultimate destination.
Then, using information in
 its routing table it directs the packet to the next
network on its journey. Routers perform the
"traffic directing" functions on the Internet. A
data packet is typically forwarded from one
router to another through the networks that
constitute the internetwork until it gets to its
destination node.
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24. Router
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25. THANK YOU
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